I don't expect journalism to be non-partisan. I expect it to be affirmatively transparent about its partisanship.
You're right, though, that nothing actually meets that bar. It's a human institution; it's necessarily flawed. That's why you source across biases and ideologies, and correct accordingly.
The thing I'm talking about is instead the deliberate pretense of not being partisan. Fox News calling itself "fair and balanced", or claiming "We report. You decide." are just particularly egregious examples. When you aren't presenting enough of the picture for someone to form an informed opinion, you're peddling propaganda. I know the propagandist can't admit that's what he's doing, so I hold journalism to the standard of integrity of knowing, and owning, its biases.
But it's ultimately a spectrum, and it's on me to gauge where on that spectrum any given source lands. Some things are more propaganda than journalism. Some things are more or less one or the other to different degrees on different topics, at the same time. Sometimes they're at different points on the same topic, on different days, or in different stories.
It's complicated, sure. But, holding as nuanced an appreciation of this mess as I hope I've implied, I hope also that you'll give me the credit of not merely talking out my ass when I say I find Assange to be towards the propagandist pole.